Pivotable bolt latch



March 8, 1960 L. D. sMrrH ETAL 2,927,812

PIvoTABLE BOLT LATCH Filed June,14. 1957 Femm/w @4a/yf@ 1N VENTORS j 2,927,812` 1V4 Y PivoTABLE oLT LATCH Lawrence D. Smith, Pacoima, and Franklin L. Sawyer, Canoga Park, Calif., assignors to Clark Hartwell, doing business as Hartwell Aviation Supply Company, Los

Angeles, Calif.

Application June 14, 1957, serial Np. 665,761

s claims. (c1. 292-496) This invention relates to pivotable bolt latches,"and included in the objects of this invention are:

*Y 'Pivotally mounted on thel sleeve 4 is a link membe 11 Ahaving an extended socket end 12 which is internally I screw-thre'aded. The socket end 12, receives a differ- First, to provide a latch which is primarily'intende'd for doors or access panels ush with surroundingstructure, and has particular application to such panels or doors provided in aircraft. j

Second, to provide a latch wherein an essentially J- j lshaped latch arm is movable between an extended and a retracted position by overcenter link elements and a handle member so arranged that the latch arm may be flocked in its extended position and loads imposed thereon `Hcannot exert releasing forces on the link elements and handle member. A `Third, to provide a latch lof this type wherein the handle lever may be mounted ush with the surrounding structure, and both an auxiliary latch and a separate 'fastener means are employed -to retain the handlein itsI ilush position so that the possibility of accidental release i l is extremely remote.

Fourth, to provide a latch of this type whereinthe latching position of the latch arm may be accurately adjusted, and in so doing the door or panel in which the latch is mounted may be brought into exactly llush rela tion with the surrounding structure.

With the above and other objects in View, as may appear hereinafter, reference is directed to the accompanying drawings in which:

Figure l is a top or plan view of the latch, the parts being in the position assumed when the latch is closed;

Fig. 2 is an enlarged longitudinal sectional view through 2 2 of Fig. l, showing the latch in its closed ,position and in engagement with a keeper member, and

also indicating by broken lines and` fragmentarily the structures in which the latch and its keeper are mounted; Fig. 3 is a view similar to 2 showing the latch in its open position, but omitting the surrounding structure and keeper member;

Figs. 4 and 5 are transverse sectional views through 4-4 and 5-5, respectively, of Fig. 2. A The latch structure includes a pair of side plates 1 which are roughly rhombic in shape. The two acute corners of the side plates are provided with connecting sleeves 3 and 4 through which extend mounting bolts 5 and 6. The mounting bolts are secured to suitable brackets or to a frame, not shown.

Journaled on the sleeve 3 is a bolt lever 7 which is substantially J-shaped. The pivotal axis of the lever isl at the en d of its longer leg, whereas the shorter leg is -provided with a shoe` Shaving lugs which iit over the ential screwv13 which is provided with a screw-threaded bore toreceive a screwv shaft 14. The pitch of the screw threads joiningthe differential screw 13 with the link member 11 is greater than the pitch of the screw threads joining the differential screw to the screw shaft-14. Thus by rotating the differential screw while therv screw shaft u14 andlink member 11 are restrained from turning causes the screw shaft 14 to extend or retract, and, de-

pending on the `selection of the relative pitches of the screw threads, an adjustment of the desired preciseness may be attained. Or, if desired, right and left pitch screw threads may be used s o that a coarseadjustment which is the sum of the 'screw threads may be obtained.

The protruding end of the differential screw 13 is provided with a slotted flange 15 to facilitate rotation. A

U-shaped-spring retainer 16 tits over the end of the link member 11 and is Vprovided with a spring leg which engages the' slots of the flange 15 to secure the differential screw 13 in various adjusted positions. i

The extended end of the screw shaft 14 terminates in an eyelet in which is tted a transverse pin 17. The pin 17l journals a pair of link bars 18, the extended ends of which are pivotally connected by a pin 19 to the vbolt lever 7 near the root end of its pivoted leg.

t, Between the lower obtuse corner defined by the side plates 1, under the link bars 18, is a stop pin 20 which is engaged by the link bars 18. The under side of the link bars 18 are provided with arcuate recesses 21. The location of the stop pin 20 and the arrangement of the re- Acesses 21 are such as to permit slightly overcenter positioning of the axis of the pin 17 relative to the plane delined by the axis of the pin 19 and the axis of the sleeve 4. By appropriate shaping of the recesses 21 this over- -center position is maintained within the limits of eX- tensionl and retraction of the screw shaft 14. When the link bars 18 engage the stop pin 20, the bolt lever 7 is in its keeper bracket-engaging position. Any loads which may be applied to the shoe 8 are transmitted to the two mounting bolts 5 and 6 with only a relatively small force component on the stop pin 20. Thus the bolt lever *'7 is rigidly locked Vwhen in its extended position. 45

Ylianges 24 and through the side plates 1 near the mounting bolt 5. The handle lever 227extends in a direction away from the'mounting bolt 5 and above the mounting bolt 6, and terminates beyond the side plates 1. The web 'V23 is intended to be positioned yflush with the doorrpanel, or other structure, B in whichy the latch is mounted. The free extremity of the web 23 is provided with fastener-receiving holer26 for securing this end to the structure B. Y

Near the journal pin '25 the side flanges 24 are prol vided with lost motion slots 27 which receive a transverse pin 28. The pin 28 journals a pair of link members 29 which extend downwardly and are joined to the'fjournalpin 17., Upon rotation of the handle lever 22about itsaxis, the link members 29 drawv upwardly onthe pin 17 causing the link member 11 and link bars 18 to fold and draw the bolt lever 7 towards its retracted position, as shown in Fig. 3.

The lost motion slots 27 permit limited initial movement of the handle lever 22. A spring 30 is wrapped around the journal pin 25 and bears between the pin 28 and web 23 so that the handle lever 22 tends to spring upwardly from the structure B through an arc deter- .PatentedMan 8, `,1969

ush position by means of an auxiliary latch member 31.'

The latch member 31 is formed of sheet material and is shaped latch lever pivotally mounted at the extremity of its longer leg and having allatch face at the extremity channel-shaped in cross section, forming la web 32 and l other end bea-rs against the web 32 to urge the auxiliary j latch member 31 into its llush position. Extensions of the side ilanges 33 form stops 38 which engage underr i the web 23 adjacent one end of the aperture 34.

The side flanges 33 project downward and terminate inV hook elements 39 which engage a keeper pin 40 disposed between upwardly projecting bosses 41 located above the mounting bolt 6. The side anges 33 above the hook elements may form cams 33aV which on pivoting of the auxiliary latch raise the handle lever 22, and thus eliminate the need of the spring 30.

Operation of the latch structure is as follows:

When the latch is in its closed or operating position, the bolt lever 7 is extended with the shoe 8 in Vengagement with the keeper bracket 10. The axis of theY pin 17 is slightly below the plane defined by the mounting bolt 6 and pin 19 so that the link bars 18 bear against the stop pin 20. Y The handle lever 22 is in its ilush position relative to the surrounding structure B and may be secured thereto by suitable means extending ythrough the hole 26. In addition the auxiliary latch member 31 is in its ilush position relative to the handle lever 22 and the hook elements 39 are in engagement with the keeper pin 40.

When it is desired to open the latch, the retaining means in the hole 26 is removed or released and the auxiliary latch member 31 is manually pivoted by pushing inward on the appropriate end of the web 32, whereupon ythe spring causes limited initial movement of the handle lever 22 so that it may be manually grasped for further movement. Further rotation of the handle lever 22 moves the handle lever to the position shown in Fig. 3.

This movement causes the link members 29 to draw up-V wardly on the pin 17, jackkniiing the link member 11 and link bars 18, so as to pivot the bolt lever 7 to its retracted position, as shown in Fig. 3.

It is essential that the upper surface of the structure B be ilush with the structure A. Leveling or adjustment of the structure B is accomplished by extending or retracting the screw shaft 14, which alters the latching position of the bolt lever 7 so that the structure B may be raised or lowered relative to the structure A, asY viewed in Fig. 2,

until the two structures are exactly ilush.

While a particular embodiment of this invention has been shown and described, it is not intended to limit the same to the exact details of the construction set forth, and it embraces such changes, modifications, and equivalents of the parts and their formation and arrangement as come within the purview of the appended claims.

What is claimed is:

1. A latch construction, comprising: an essentially J- of its shorter leg; a pair of tandem-disposed link units pivotally joined to each other for relative movement about an intermediate axis,-one of said link units being pivotally joined to said latch lever, the other link unit having a remote pivotal axis; a link means connected to said link units for moving said intermediate pivotal connection laterally, .thereby to pivot said latch lever between an extended latching position and a retracted position; means incorporated in one of said link units for adjusting the effective length thereof, thereby to alter the location of the latching position ofthe latch lever; a handlelever pivotally mounted by one end; a lost motion connection between said handle lever and said link means to permit limited free movement of said handle lever, said handle lever being operable to move said link means thereby to effect movement of said latch lever; and an auxiliary latch member carried by said handle lever including hook means, and an auxiliary keeper'engageable by said hook means.

K 2. A latch construction, comprising: a pair of sid plates; a latch lever pivotally mounted therebetween; a pair of tandem-disposed link units pivotally joined to each other about an intermediate axis, one of said link units being pivotally connected to said latch lever about one extreme axis, the remote end of the other link unit being pivotally connected between said side plates about the other extreme axis; a laterally directed link means joined to said link elements for displacing said intermediate axis laterally between said extreme axes, thereby to elect pivotalmovement of said latch lever between an extended latching position and a retracted position; a handle lever also rpivotally mounted by one end between Vsaid side plates; and a lost motion connection between said handle lever and said link means to permit limited free movement of said handle lever, said handle lever being operable to move said link means thereby to effect movement of said latch lever.

3. A latch construction, comprising: a pair of side plates; a latch lever pivotally mounted therebetween; a pair of tandem-disposed link units pivotally joined -to each other aboutV an intermediate axis, one of said link units being pivotally connected to saidlatch lever about one extreme axis, the remote end of the other link unit being pivotally connected between said side plates about the other extreme axis; a laterally directed link means joined to said link elements for displacing said intermediate axis laterally between said extreme axes; thereby to effect pivotal movement of said latch lever between an extended latching position and a retracted position; a handle lever also pivotally mounted by one end between said side plates; a lost motion connection between said handle lever and said link means to permit limited free movement of said handle lever, said handle lever being operable to move said link means thereby to effectw movement of said latch lever; and an auxiliary latch member carried by said handle lever including hook means, and an auxiliary keeper carried by said side plates engageable by said hook means. Y

North Aug. 6, i940 schetky Mar. 1s, 1952 

